Revert "Enable CentralNotice CrossWiki Hiding"

Uncacheable Special:HideBanners requests hit the mobile Varnishes and
overloading them. Revert until there are proper caching headers set.

This reverts commit f565c5cd99729cce0e523806e8de33b9fe722036.

Change-Id: I866838bc2244bca8be521309237bd9a601758fe3
Merge "Revert "Enable CentralNotice CrossWiki Hiding""